src/snap.h

   1 /**
   2  * \file snap.h
   3  * \brief Per-desktop object that handles snapping queries
   4  *//*
   5  * Authors:
   6  *   Lauris Kaplinski <lauris@kaplinski.com>
   7  *   Frank Felfe <innerspace@iname.com>
   8  *   Carl Hetherington <inkscape@carlh.net>
   9  *   Diederik van Lierop <mail@diedenrezi.nl>
  10  *
  11  * Copyright (C) 2006-2007 Johan Engelen <johan@shouraizou.nl>
  12  * Copyright (C) 2000-2002 Lauris Kaplinski
  13  * Copyright (C) 2000-2010 Authors
  14  *
  15  * Released under GNU GPL, read the file 'COPYING' for more information
  16  */
  17
  18 #ifndef SEEN_SNAP_H
  19 #define SEEN_SNAP_H
  20
  21 #include <vector>
  22 #include "guide-snapper.h"
  23 #include "object-snapper.h"
  24 #include "snap-preferences.h"
  25
  26 /* Guides */
  27 enum SPGuideDragType { // used both here and in desktop-events.cpp
  28     SP_DRAG_TRANSLATE,
  29     SP_DRAG_ROTATE,
  30     SP_DRAG_MOVE_ORIGIN,
  31     SP_DRAG_NONE
  32 };
  33
  34 class SPNamedView;
  35
  36 /// Class to coordinate snapping operations
  37 /**
  38  * The SnapManager class handles most (if not all) of the interfacing of the snapping mechanisms
  39  * with the other parts of the code base. It stores the references to the various types of snappers
  40  * for grid, guides and objects, and it stores most of the snapping preferences. Besides that
  41  * it provides methods to setup the snapping environment (e.g. keeps a list of the items to ignore
  42  * when looking for snap target candidates, and toggling of the snap indicator), and it provides
  43  * many different methods for snapping queries (free snapping vs. constrained snapping,
  44  * returning the result by reference or through a return statement, etc.)
  45  *
  46  * Each SPNamedView has one of these.  It offers methods to snap points to whatever
  47  * snappers are defined (e.g. grid, guides etc.).  It also allows callers to snap
  48  * points which have undergone some transformation (e.g. translation, scaling etc.)
  49  *
  50  * \par How snapping is implemented in Inkscape
  51  * \par
  52  * The snapping system consists of two key elements. The first one is the snap manager
  53  * (this class), which keeps some data about objects in the document and answers queries
  54  * of the type "given this point and type of transformation, what is the best place
  55  * to snap to?".
  56  *
  57  * The second is in event-context.cpp and implements the snapping timeout. Whenever a motion
  58  * events happens over the canvas, it stores it for later use and initiates a timeout.
  59  * This timeout is discarded whenever a new motion event occurs. When the timeout expires,
  60  * a global flag in SnapManager, accessed via getSnapPostponedGlobally(), is set to true
  61  * and the stored event is replayed, but this time with snapping enabled. This way you can
  62  * write snapping code directly in your control point's dragged handler as if there was
  63  * no timeout.
  64  */
  65
  66 class SnapManager
  67 {
  68 public:
  69     enum Transformation {
  70         TRANSLATE,
  71         SCALE,
  72         STRETCH,
  73         SKEW,
  74         ROTATE
  75     };
  76
  77     SnapManager(SPNamedView const *v);
  78
  79     typedef std::list<const Inkscape::Snapper*> SnapperList;
  80
  81     bool someSnapperMightSnap() const;
  82     bool gridSnapperMightSnap() const;
  83
  84     void setup(SPDesktop const *desktop,
  85             bool snapindicator = true,
  86             SPItem const *item_to_ignore = NULL,
  87             std::vector<Inkscape::SnapCandidatePoint> *unselected_nodes = NULL,
  88             SPGuide *guide_to_ignore = NULL);
  89
  90     void setup(SPDesktop const *desktop,
  91                bool snapindicator,
  92                std::vector<SPItem const *> &items_to_ignore,
  93                std::vector<Inkscape::SnapCandidatePoint> *unselected_nodes = NULL,
  94                SPGuide *guide_to_ignore = NULL);
  95
  96     void setupIgnoreSelection(SPDesktop const *desktop,
  97                               bool snapindicator = true,
  98                               std::vector<Inkscape::SnapCandidatePoint> *unselected_nodes = NULL,
  99                               SPGuide *guide_to_ignore = NULL);
 100
 101     void unSetup() {_rotation_center_source_items = NULL;
 102                     _guide_to_ignore = NULL;
 103                     _desktop = NULL;
 104                     _unselected_nodes = NULL;}
 105
 106     // If we're dragging a rotation center, then setRotationCenterSource() stores the parent item
 107     // of this rotation center; this reference is used to make sure that we do not snap a rotation
 108     // center to itself
 109     // NOTE: Must be called after calling setup(), not before!
 110     void setRotationCenterSource(GSList *items) {_rotation_center_source_items = items;}
 111     GSList const *getRotationCenterSource() {return _rotation_center_source_items;}
 112
 113     // freeSnapReturnByRef() is preferred over freeSnap(), because it only returns a
 114     // point if snapping has occurred (by overwriting p); otherwise p is untouched
 115     void freeSnapReturnByRef(Geom::Point &p,
 116                                 Inkscape::SnapSourceType const source_type,
 117                                 Geom::OptRect const &bbox_to_snap = Geom::OptRect()) const;
 118
 119     Inkscape::SnappedPoint freeSnap(Inkscape::SnapCandidatePoint const &p,
 120                                     Geom::OptRect const &bbox_to_snap = Geom::OptRect() ) const;
 121
 122     void preSnap(Inkscape::SnapCandidatePoint const &p);
 123
 124     Geom::Point multipleOfGridPitch(Geom::Point const &t, Geom::Point const &origin);
 125
 126     // constrainedSnapReturnByRef() is preferred over constrainedSnap(), because it only returns a
 127     // point, by overwriting p, if snapping has occurred; otherwise p is untouched
 128     void constrainedSnapReturnByRef(Geom::Point &p,
 129                                     Inkscape::SnapSourceType const source_type,
 130                                     Inkscape::Snapper::SnapConstraint const &constraint,
 131                                     Geom::OptRect const &bbox_to_snap = Geom::OptRect()) const;
 132
 133     Inkscape::SnappedPoint constrainedSnap(Inkscape::SnapCandidatePoint const &p,
 134                                            Inkscape::Snapper::SnapConstraint const &constraint,
 135                                            Geom::OptRect const &bbox_to_snap = Geom::OptRect()) const;
 136
 137     Inkscape::SnappedPoint multipleConstrainedSnaps(Inkscape::SnapCandidatePoint const &p,
 138                                                         std::vector<Inkscape::Snapper::SnapConstraint> const &constraints,
 139                                                         Geom::OptRect const &bbox_to_snap = Geom::OptRect()) const;
 140
 141     Inkscape::SnappedPoint constrainedAngularSnap(Inkscape::SnapCandidatePoint const &p,
 142                                                     boost::optional<Geom::Point> const &p_ref,
 143                                                     Geom::Point const &o,
 144                                                     unsigned const snaps) const;
 145
 146     void guideFreeSnap(Geom::Point &p, Geom::Point const &guide_normal, SPGuideDragType drag_type) const;
 147     void guideConstrainedSnap(Geom::Point &p, SPGuide const &guideline) const;
 148
 149     Inkscape::SnappedPoint freeSnapTranslate(std::vector<Inkscape::SnapCandidatePoint> const &p,
 150                                                Geom::Point const &pointer,
 151                                                Geom::Point const &tr) const;
 152
 153     Inkscape::SnappedPoint constrainedSnapTranslate(std::vector<Inkscape::SnapCandidatePoint> const &p,
 154                                                       Geom::Point const &pointer,
 155                                                       Inkscape::Snapper::SnapConstraint const &constraint,
 156                                                       Geom::Point const &tr) const;
 157
 158     Inkscape::SnappedPoint freeSnapScale(std::vector<Inkscape::SnapCandidatePoint> const &p,
 159                                          Geom::Point const &pointer,
 160                                          Geom::Scale const &s,
 161                                          Geom::Point const &o) const;
 162
 163     Inkscape::SnappedPoint constrainedSnapScale(std::vector<Inkscape::SnapCandidatePoint> const &p,
 164                                                 Geom::Point const &pointer,
 165                                                 Geom::Scale const &s,
 166                                                 Geom::Point const &o) const;
 167
 168     Inkscape::SnappedPoint constrainedSnapStretch(std::vector<Inkscape::SnapCandidatePoint> const &p,
 169                                                   Geom::Point const &pointer,
 170                                                   Geom::Coord const &s,
 171                                                   Geom::Point const &o,
 172                                                   Geom::Dim2 d,
 173                                                   bool uniform) const;
 174
 175     Inkscape::SnappedPoint constrainedSnapSkew(std::vector<Inkscape::SnapCandidatePoint> const &p,
 176                                                Geom::Point const &pointer,
 177                                                Inkscape::Snapper::SnapConstraint const &constraint,
 178                                                Geom::Point const &s, // s[0] = skew factor, s[1] = scale factor
 179                                                Geom::Point const &o,
 180                                                Geom::Dim2 d) const;
 181
 182     Inkscape::SnappedPoint constrainedSnapRotate(std::vector<Inkscape::SnapCandidatePoint> const &p,
 183                                                     Geom::Point const &pointer,
 184                                                     Geom::Coord const &angle,
 185                                                     Geom::Point const &o) const;
 186
 187     Inkscape::GuideSnapper guide;      ///< guide snapper
 188     Inkscape::ObjectSnapper object;    ///< snapper to other objects
 189     Inkscape::SnapPreferences snapprefs;
 190
 191     SnapperList getSnappers() const;
 192     SnapperList getGridSnappers() const;
 193
 194     SPDesktop const *getDesktop() const {return _desktop;}
 195     SPNamedView const *getNamedView() const {return _named_view;}
 196     SPDocument *getDocument() const;
 197     SPGuide const *getGuideToIgnore() const {return _guide_to_ignore;}
 198
 199     bool getSnapIndicator() const {return _snapindicator;}
 200
 201     Inkscape::SnappedPoint findBestSnap(Inkscape::SnapCandidatePoint const &p, SnappedConstraints const &sc, bool constrained, bool noCurves = false, bool allowOffScreen = false) const;
 202
 203 protected:
 204     SPNamedView const *_named_view;
 205
 206 private:
 207     std::vector<SPItem const *> _items_to_ignore; ///< Items that should not be snapped to, for example the items that are currently being dragged. Set using the setup() method
 208     GSList *_rotation_center_source_items; // to avoid snapping a rotation center to itself
 209     SPGuide *_guide_to_ignore; ///< A guide that should not be snapped to, e.g. the guide that is currently being dragged
 210     SPDesktop const *_desktop;
 211     bool _snapindicator; ///< When true, an indicator will be drawn at the position that was being snapped to
 212     std::vector<Inkscape::SnapCandidatePoint> *_unselected_nodes; ///< Nodes of the path that is currently being edited and which have not been selected and which will therefore be stationary. Only these nodes will be considered for snapping to. Of each unselected node both the position (Geom::Point) and the type (Inkscape::SnapTargetType) will be stored
 213
 214     Inkscape::SnappedPoint _snapTransformed(std::vector<Inkscape::SnapCandidatePoint> const &points,
 215                                             Geom::Point const &pointer,
 216                                             bool constrained,
 217                                             Inkscape::Snapper::SnapConstraint const &constraint,
 218                                             Transformation transformation_type,
 219                                             Geom::Point const &transformation,
 220                                             Geom::Point const &origin,
 221                                             Geom::Dim2 dim,
 222                                             bool uniform) const;
 223
 224     Geom::Point _transformPoint(Inkscape::SnapCandidatePoint const &p,
 225                                             Transformation const transformation_type,
 226                                             Geom::Point const &transformation,
 227                                             Geom::Point const &origin,
 228                                             Geom::Dim2 const dim,
 229                                             bool const uniform) const;
 230
 231     void _displaySnapsource(Inkscape::SnapCandidatePoint const &p) const;
 232 };
 233
 234 #endif /* !SEEN_SNAP_H */
 235
 236 /*
 237   Local Variables:
 238   mode:c++
 239   c-file-style:"stroustrup"
 240   c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
 241   indent-tabs-mode:nil
 242   fill-column:99
 243   End:
 244 */
 245 // vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4 :